1. Field of the Invention
The present invention relates to a poultry eggshell strengthening composition capable of enhancing the strength of poultry eggshells by addition to feeds for poultry, such as fowl, and feeding it to the poultry.
2. Description of the Background
Eggs of poultry, such as fowl, are often broken when laid, or during handling steps including egg collection, selection, washing, packaging, transportation, display, selling, storage, and the like. The strength of poultry eggs relates to the eggshell structure and correlates to the thickness and specific gravity of the eggshell [see, Shinpen Chikusan Daijiten, p. 463, published by Yokendo]. The eggshell structure is composed of the eggshell, the eggshell membrane and the cuticle. A fowl eggshell weighs about 5 g on average, has a thickness of from 300 to 360 xcexcm and is composed of about 98% inorganic matter (98.4% calcium carbonate with magnesium carbonate and calcium phosphate each in a trace amount) and about 2% organic matter, by weight. A fowl eggshell membrane has a thickness of about 70 xcexcm and consists of the external eggshell membrane and the internal eggshell membrane. At the obtuse end of the egg, the external eggshell membrane and the internal eggshell membrane split forming the air chamber The eggshell membrane is composed of about 90% proteins, about 3% lipids and about 2% saccharides, by weight. A fowl egg cuticle is a shapeless coating formed on the surface of the eggshell immediately after egg-laying, from the drying of gelatinous material secreted at egg laying. It is composed of about 85% to 87% proteins, about 3.5% to 3.7% saccharides and about 2.5% to 3.5% lipids, by weight. The eggshell thickness varies depending on temperature and age. Namely, eggshell thickness becomes thinner at higher temperatures or as aging proceeds.
Since calcium is the major component of eggshell, the blood calcium level would relate to the formation of eggshell. Calcium absorbed from the intestinal tract is first accumulated in the femora and then liberated, when necessary, into the blood in the form of osteoblasts, thus participating in the eggshell formation. Therefore, poultry eggshells can be thickened by promoting the absorption and metabolism of calcium. Although the role of the eggshell membrane is not known in detail, it is assumed that the eggshell can be strengthened as the eggshell membrane is thickened together with the eggshell.
Attempts have been made to thicken poultry eggshell by, for example, adding various calcium materials to feeds, improving feeding methods, or administering CPP (casein phospho peptide) and CCM (calcium citrate malate). However, no method has been developed which is satisfactory for those concerned with large scale egg collection having a small profit margin. Thus, there has been a need to develop techniques whereby poultry eggshell can be strengthened by convenient procedures.
It is reported that various viable microorganism preparations contribute to poultry body weight gain, improvement in meat qualities, increase in the ratio of egg laying, suppression and decrease in harmful enterobacteria bacteria, and the like. These preparations have been already put into practical use for various purposes. It is also reported that eggshells can be slightly thickened and the ratio of eggs with thin eggshell can be reduced by adding a preparation containing Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum, Aspergillus oryzae and Torulopsis sp. to a feed. However, it has not reported that this preparation achieves a strengthening effect to such a level sufficient to show a significant difference. Moreover, it has never clarified which microorganism exerts the eggshell strengthening effect.
It has been necessary to improve the economical efficiency of poultry farming, since the techniques for increasing feed efficiency ratio and egg laying ratio have been advanced. As a result, there arises a tendency toward intensive poultry farming In association with large-scaled poultry farming, egg collection, selection, washing and packaging are being mechanized. Under these circumstances, it is very important to strengthen the eggshells and external eggshell membranes to improve the resistance to breakage during transportation, display, selling, and the like. Thickening and strengthening of eggshells and external eggshell membranes bring about another advantage in that the resistances against bacteria and oxygen-permeability are also improved and the shelf life of the eggs is consequently prolonged. Therefore, there is a need to develop a practically effective poultry eggshell strengthening composition mainly by those concerned in poultry farming.
An object of the present invention is to provide a poultry eggshell strengthening composition capable of enhancing eggshell thickness and external eggshell membrane thickness, effectively, in practice, when simply added to poultry feed, and the like.
This and other objects of the present invention have been accomplished by a poultry eggshell strengthening composition for enhancing eggshell thickness and external eggshell membrane thickness, comprising a viable microorganism belonging to Bacillus subtilis as an active ingredient, optionally together with a carrier or diluent.
Furthermore, this and other objects of the present invention have been accomplished by a method for enhancing eggshell thickness and external eggshell membrane thickness, comprising administrating to a poultry in need thereof an effective amount of a poultry eggshell strengthening composition comprising a viable microorganism belonging to Bacillus subtilis as an active ingredient, optionally together with a carrier or diluent.
The viable microorganism contained in the poultry eggshell strengthening composition of the present invention as the active ingredient belongs to Bacillus subtilis, and the microbiological properties thereof are described in Bergey""s Manual of Bacteriology, Vol. 11 (1986). More specifically, it is preferred to use Bacillus subtilis C-3102 having improved effect for strengthening poultry eggshell (Deposit No.: FERM BP-1096; Name of depositary institution: Fermentation Research Institute, Agency of Industrial Science and Technology (present name: National Institute of Bioscience and Human-Technology, Agency of Industrial Science and Technology); Address of depositary institution: 1-3, Higashi 1 chome, Yatabe-machi, Tsukuba-gun, Ibaraki-ken 305 Japan (present address: 1-3, Higashi 1 chome, Tsukuba-shi, Ibaraki-ken 305 Japan); Date of deposit: Jun. 28, 1986). Many different strains of Bacillus subtilis are known, such as those described in ATCC Bacteria and Bacteriophages, 19th ed., 1996, pages 57-63, hereby incorporated by reference.
The Bacillus subtilis as described above can be cultured in a liquid or solid medium containing carbon sources, nitrogen sources, inorganic matter, and the like commonly employed in media for culturing microorganisms. Any carbon source may be used, so long as it can be metabolized by Bacillus subtilis. For example, glucose, fructose, sucrose, starch and molasses. Examples of the nitrogen source include peptone, casein hydrolyzate, meat extract and ammonium sulfate. If necessary, the medium may further contain phosphoric acid, salts of potassium, magnesium, calcium, sodium, iron, manganese and the like, vitamins, amino acids, surfactant, and the like. It is preferred to perform the culture aerobically. With respect to the culture condition, it is preferred to use, for example, a liquid medium contained in a jar-fermenter under aeration/agitation, a solid medium of the plate-type or an automated koji-producing fermenter. Culturing is performed at a temperature of 20 to 50xc2x0 C., preferably 30 to 45xc2x0 C., for 12 hours to 7 days at a culture pH value of 5 to 9, preferably 6 to 8.
The culture thus obtained may be employed either as such or after concentration. Alternatively, the microorganisms harvested from the culture may be employed either as such or processed together with fillers and the like into a dry powder or granules. As the fillers, examples include calcium carbonate, corn grits, corn flour, defatted rice bran, wheat bran, skim milk powder, and the like.
The eggshell strengthening composition of the present invention may contain a carrier or diluent. The carrier and diluent are not particularly limited, and selected from pharmaceutically or nutritionally acceptable carriers and diluents.
In the present invention, the microorganism belonging to, Bacillus subtilis may be subjected to an appropriate mutation treatment, such as exposure to ultraviolet light, X-ray or radiation, and a chemical treatment with a mutagenic compound (e.g., nitrsoguanidine, acridine dye). Mutants may also be prepared by insertion, deletion or substitution of nucleotides, as well as spontaneous mutation. The thus obtained mutants can be used in the present invention as far as they are capable of enhancing eggshell thickness and external eggshell membrane thickness. The term Bacillus subtilis includes these mutants.
The eggshell strengthening composition of the present is invention preferably contains from 106 to 1011 per g of the Bacillus subtilis viable microorganism preparations in the form of spores and/or nutritive cells.
It is thought that the eggshell strengthening composition of the present invention promotes the absorption and metabolism of calcium required by poultry so as to enhance the eggshell thickness or external the eggshell membrane thickness. Accordingly, it may be added to, for example, a formula feed for poultry which contains calcium in a sufficient amount needed for egg-laying poultry. It may be administered in an arbitrary method without restriction. In a preferred case, it is processed into preparations which can be uniformly added to marketed feeds and easily given to poultry, in particular, powders. The effective concentration of the eggshell strengthening composition varies depending on the type and age of the poultry, and the like. For example, it may be added to a marketed feed for poultry preferably in such an amount as to give a viable count of 103 to 107 viable microorganisms per g, more preferably 104 to 106 per g, to prepare a feed for strengthening poultry eggshell. When the viable count is less than 103 per g, no significant effect is achieved. On the other hand, it is not advantageous from an economical viewpoint that the viable count exceeds 107 per g, since there is a risk that the increase in cost due to the addition of the viable microorganism preparation might exceed the cost caused by broken eggs.
The poultry whose eggshell thickness and external eggshell membrane thickness are to be enhanced according to the present invention are not particularly restricted. Examples thereof include fowl (chicken), duck, bantam, goose and quail.